1. Field of the Invention
The present invention relates to a silicone rubber composition curable by a radial ray, especially useful as a sealant of an electric and electronic part.
2. Description of the Related Art
An organopolysiloxane composition curable by irradiation of a radial ray such as an UV beam has been already known. For example, an organopolysiloxane composition comprising an organopolysiloxane having a vinyl functional group and a photo-polymerization initiator is excellent as a coating material for an optical fiber curable by a radial ray (Patent Document 1). However, this composition is left as an uncured liquid if not irradiated with an UV beam so that there has been an instance that this flows into a device having this coated part thereby causing pollution.
This drawback could be remedied by an organopolysiloxane composition (Patent Document 2) comprising at least a certain organopolysiloxane having radial-ray reactive (meth)acryloyl groups in its both chain terminals, a photosensitizer, and a tetraalkyl silane or its partially-hydrolyzed condensate; but this could not fully satisfy the recent requirement of high curing rate nor the requirement of lower light intensity of a radial ray during curing. In addition, a problem of uncured state occurred during the trouble of an UV-beam irradiating equipment.